Table 1.

Comparison of experimental excitation energies (in electronvolts) with vertical excitation calculations at the MS-CASPT2, CASSCF, MRCIS, ADC(2) and TD-DFT levels of theory. For all calculations, the CASSCF geometry from [17] was used. Orbital labels refer (approximately) to figure 2a, except for MRCIS (those refer to figure 2b).

		MS-CASPT2a			CASSCFb			MRCISc			ADC(2)d			TD-BP86e			TD-B3LYPf
state	exp. [48]	E	fosc	char.	E	fosc	char.	E	fosc	char.	E	fosc	char.	E	fosc	char.	E	fosc	char.
S0		0.00	—	cs	0.00	—	cs	0.00	—	cs	0.00	—	cs	0.00	—	cs	0.00	—	cs
S1	4.66	4.60	0.30		5.02	0.00		5.09	0.00		4.75	0.00		4.10	0.00		4.66	0.12
S2		4.92	0.00		6.17	0.00	π4σ*CBr	6.08	0.29		4.95	0.21		4.23	0.08		4.78	0.00
S3		5.47	0.00	π4σ*CBr	6.76	0.59		6.21	0.00	π4σ*CBr	5.64	0.00	π4σ*CBr	4.69	0.00		4.98	0.00	π4σ*CBr
S4	6.12	6.01	0.03		7.61	0.01		7.74	0.11		6.04	0.00		4.73	0.00	π4σ*CBr	5.43	0.00
S5		6.23	0.00		7.99	0.00		8.13	0.01		6.20	0.04		4.87	0.00		5.79	0.00
S6		6.55	0.00		8.52	0.00		8.36	0.00		6.42	0.00		5.01	0.00		5.88	0.06
S7		6.61	0.00		8.66	0.03		8.59	0.14		6.64	0.26		5.20	0.05		5.90	0.00	π4Ryd
S8	7.20	7.08	0.00		8.83	0.00		8.64	0.00		6.74	0.00		5.45	0.09		6.08	0.12
T1	3.35	3.51	—		3.81	—		3.92	—		3.63	—		3.23	—		3.20	—
T2		4.78	—		4.88	—		4.82	—		4.55	—		3.89	—		4.43	—
T3		5.01	—	π4σ*CBr	5.69	—		5.68	—	π4σ*CBr	5.16	—	π4σ*CBr	4.35	—	π4σ*CBr	4.53	—	π4σ*CBr
T4		5.16	—		5.93	—	π4σ*CBr	6.31	—		5.36	—		4.51	—		4.75	—
T5		5.91	—		6.83	—		7.87	—		5.90	—		4.64	—		5.20	—
T6		6.05	—		7.80	—		8.00	—		6.00	—		4.73	—		5.37	—
T7		6.24	—		8.02	—	π3σ*CBr	8.05	—		6.03	—		4.76	—		5.56	—
T8		6.99	—		8.34	—		8.24	—		6.38	—		4.94	—		5.58	—
	RMSD	0.00			1.01			0.75			0.21			0.67			0.34

^aMS-CASPT2(20,14)/ANO-RCC-VDZP. S₀ energy: −3017.895007 atomic units. ^bCASSCF(14,11)/cc-pVDZ-DK. S₀ energy: −3016.429666 atomic units. ^cMRCIS(10,8)/cc-pVDZ-DK. S₀ energy: −3016.550517 atomic units.^dADC(2)/def2-TZVP. S₀ energy: −2986.073460 atomic units. ^eTD-BP86/TZP. S₀ binding energy: −2.845430 atomic units. ^fTD-B3LYP/TZP. S₀ binding energy: −3.361766 atomic units.